another bullet seating depth question

[jon1163]

Hey all thanks for the help.

I reload .380, 9mm and .45 only. Most of the articles on bullet seating depth talk about rifles...is there a difference in technique? I have a few questions here.

Things I think I understand:
1. I understand that a longer OAL can raise pressures
2. I understand some different methods for checking OAL although I've never done it.
3. I've reloaded quite a few boxes of .45 without making sure my OAL was .01 or whatever short of the lands.

Questions:
1. Up until now I've been reloading only hardball handgun cartridges. I measure a factory hardball round's length and match mine to it. Is this a dangerous method?

2. Is it absolutely necessary to do this measuring to the lands thing or is it just an extreme accuracy technique?

3. Can't I just seat the bullet then measure the overall cartridge length (from base to tip) to the specifications laid out in my reloading manual?

Thanks and any additional information would be appreciated.

J.

[Sport45]

Things I think I understand:
1. I understand that a longer OAL can raise pressures
Actually it's shorter OAL that can dramatically raise pressure when the bullet is pressed too far into the case.
2. I understand some different methods for checking OAL although I've never done it.
For handgun cartridges simply measuring from base to tip with a pair of calipers is usually fine.
3. I've reloaded quite a few boxes of .45 without making sure my OAL was .01 or whatever short of the lands.
So have I. Thousands of rounds worth.

Questions:
1. Up until now I've been reloading only hardball handgun cartridges. I measure a factory hardball round's length and match mine to it. Is this a dangerous method?
No, that should work fine. What I do is back out the seater stem and seater die body and place a known good cartridge with the same type bullet I'm loading, factory or reload, in my press. I'll raise the ram fully and then screw the die in until I feel it touch the top of the case and I'll screw it in another 1/8 turn. I'll then turn the seater stem in until i feel it touch the top of the bullet and I'll give it another 1/8 turn as well. In my press that will duplicate the length and crimp of the pattern round.

2. Is it absolutely necessary to do this measuring to the lands thing or is it just an extreme accuracy technique?
That's a rifle thing for accuracy.

3. Can't I just seat the bullet then measure the overall cartridge length (from base to tip) to the specifications laid out in my reloading manual?
That will work.

Enjoy your new hobby!

[Dingoboyx]

I use teflon coated lead projectiles and the reloads are fired thru a marlin levergun and vaquaro pistols. I havent had any trouble with seating projectiles as they have a canalure (groove) for the mouth of the case to crimp into. I just use this canelure because in the rifle (with a tubular magazine) I cant risk the projectile being forced too deep into the case once loaded in the tube mag. I have seen people seat the projectile into the second canalure once the cases get a bit shorter (to keep the projectile closer to the rifling) and from what I have been told, a longer actual overall length wouldnt cause extra pressure, more likely less pressure if anything. I might be wrong. From what I know, the main reason for people sit the projectile out further is to have the projectile closer to (or into) the rifling to avoid the projectile skidding (failing to grip the rifling) if there is a gap between the projectile at rest in the case and the beginning of the rifling.

IMO, if you find the spec. length of your round, or use a quality factory round as a guide to the correct length, then make sure yours are pretty well the same, you should be fine. If your cases are a bit short from successive reloading, dont crimp between canalures, either crimp as usual under the top one, or go for the second one (as long as you dont make the finished round too much over the spec length. Factory crimp dies are good to make sure you have a good crimp.

Muzza

[Sport45]

Muzza,

That's all good advice, but the cartridges he's loading won't have cannelures. The .380, 9mm, and .45acp headspace off the mouth of the case and use a taper crimp.

If by .45 he meant .45C, it usually does have a cannelure and will use a roll crimp as you mentioned.

[SL1]

Jon1163,

It is important that you understand a couple of things for the sake of safety:

(1) There are several effects of changing cartridge length, but which ones are most significant depends on the type of gun the cartridge is used in. You are thinking about the factors that are important in rifles, but you are loading for autofeeding pistols. The effects on pressure are generally OPPOSITE in those two types of guns. In the short pistol cases, the most important factor is the percentage change in the space for the powder when you seat the bullet to a different depth in the case. Shorter cartridge length leaves less space and causes higher pressures. Unless you are using a target pistol, there is usually some jump to the rifling for the longest cartridge length that can fit into the magazine of the pistol. (Some target .45 barrels are designed to let lead SWC shaped-bullets be seated long enough to get the SWC shoulder to touch the rifling, but that is typically done with low-power target loads.)

(2) Changing cartridge length in short pistol cases can change pressures A LOT. So, it is best to use the length that is specified in the data you have for the bullet you are using. IF you have feeding problems with the cartidge a that length, then you will need to adjust it slightly in or out to get it to feed reliably.

SL1

[tarpon]

I have been reloading for years, way too many now. I always use the reloading manuals to get the maximum performance from my reloaded ammo, depending on what I am trying to achieve.

All the data you requested is in the manuals, I would buy the manuals that are for the bullets you use -- Hey I think I have them all. There are plenty of reloading tips in the various reloader manuals as well. I use a digital dial caliper and a simple digital micrometer for diameters for all my measuring, you can get one for under $30 that works well. If you can afford only one measuring instrument, then the digital caliper is the one you want. Generally the dimensions for the reloaded cartridge with the bullet you choose is also included. If you get more serious with reloading, yo can tailor the bullet-cartridge to the rifle you are using. I have done this and it can improve accuracy slightly.

All that reading can make for even more interesting things to do -- And I would stick to manual recommendations until you throughly understand the nuances of the changes you want to make. Then make small changes and observe what results. That's where good measuring tools come into play. That's what makes reloading so much fun.

I found that always looking up the data in books before starting a loading project, helps to prevent me from assuming something that I think is true, but isn't ... ^_*. As I get older that seems to apply more.

Good habits make for good ammo and less accidents. It's not what everybody does, it's just what I do ...